At the beginning of the 20th century the need to have a tridimensional control of the tooth movement in orthodontic treatments was visualized. That is why the first brackets were developed. These were attached to the teeth by means of bands which in turn were bonded to the teeth; these first designs, in which the slot was perpendicular to the bracket base, assumed the inclination of the teeth; therefore, the clinicians had to bend the archwires in order to compensate the different inclinations presented by the slots, so the orthodontic treatments were totally craftsmanlike. In the early 1970's, the bracket fastening system to the teeth was changed, and a mesh was added to the base for the direct bonding to the enamel, thus eliminating the need to use bands. In the same decade the first system of preadjusted brackets was developed, these brackets already presented a prescription developed by measuring the inclination presented by the tooth labial (external) surface; from then on, the development of numerous preadjusted systems was started, each one with a different prescription, but with the same aim of placing the teeth in suitable positions without the need to perform bendings in the archwires, which nowadays is known to be wrong, because there are many aspects making persons different from each other. Nowadays clinicians are forced by this situation to make bends in the archwires in order to achieve the tooth positions suitable to each individual.
All of the preadjusted systems initially designed and still prevailing have control of the 1st, 2nd and 3rd order movements; the first order-movement control is achieved by modifying the bracket base thickness, the second order-movement control is achieved by inclining the bracket body in relation to the base in the mesio-distal sense, the third order movements are achieved in two ways: 1) inclining the base in relation to the body (torque in the base) and 2) by the inclination of the slot inside the bracket body (torque in the face). This should force the clinicians to have a very precise clinical view. That is why, and in order to avoid those drawbacks, we developed a novel totally adjustable bracket fitting to the dental characteristics of each individual.
The bracket: Among other alloys, it may be manufactured with stainless steel and consists of three separated parts (FIGS. 1, 2 and 3); a base (1), a body (2) and a self-ligating clasp (3) ready to be joined. Each part displays six surfaces: lingual, labial, mesial, distal, gingival and occlusal.
The base: On its lingual surface (FIG. 4) it displays a mesh for bonding to the enamel (4), the center of this surface shows a rectangular retentive depression designed to receive one of the welding machine points (5), the base lingual surface may be flat (FIG. 5) (6) or concave (FIG. 6) (7) depending on the tooth where it will be placed. The base labial surface (FIG. 7) shows a central concavity, designed to articulate and join to the lingual surface of the body (8); within the concavity silver solder may be added (9) to seal the joint when the base is attached to the body by electrical spot welding. On its mesial (10), distal (11) and gingival (12) ends the base has three indentations for identifying and for holding to the spot welding machine. The base width dimensions vary depending on the tooth where the base is going to be placed. In a mesiodistal view (FIG. 8) the base has an inclination representing the torque prescription in the base which is different for each tooth (13). The base thickness (FIG. 9) may vary depending on the tooth where it will be placed (14), modifying the tooth position in the labial-lingual sense.
The body: Its lingual surface has a convex shape (FIG. 10) (15) for articulating and joining to the concavity on the base labial surface (8); this allows to have ten degrees of rotation in the occluso-gingival sense (torque), ten degrees clockwise or counterclockwise (angulation), and five degrees of rotation in the mesio-distal sense (anti-rotation). On its labial surface the body has two pairs of retentive wings (FIG. 11) which may be used to place elastic chains or metallic ligatures. Each pair of wings is located on mesial (16) and distal (17) of the body, and the wings in each pair show an occlusal (18) and gingival disposition (19). On its labial portion each wing has a groove (20) for the insertion of the self-ligating clasp. Hooks for holding elastics may be added to the gingival wings (21), as well as an identifying mark on the distogingival wing (22). In the space between the wings of each pair, in the occlusogingival sense, there is a horizontal slot of rectangular shape spanning from mesial to distal of the body (23). The slot dimensions are 0.02235×0.028″, and it is used to insert principal archwires. In the space between the mesial and distal pairs of wings there is a vertical slot (24) deeper than the horizontal one, used for the insertion of one of the welding device points in order to join the bracket body with the base. The center of the vertical slot shows an identifying number in order to determine the tooth corresponding to the bracket (25). In a mesiodistal view (FIG. 12) the convex shape of the lingual surface is observed (15), as well as the retentive shape of the wings (16, 18, 19).
The self-ligating clasp: This moving element is inserted in the grooves that the wings have on their labial surface (20). The clasp is introduced in a gingivo-occlusal direction (FIGS. 13 and 14). This accessory shows a novel dual system which the clinician may place and remove at will. It is designed for use in low-friction mechanics, or for use in the traditional ligating system. The clasp is presented in three modalities: 1) low-friction clasp (FIG. 15), with two parallel arms (26) and a connector (27). The arms have indentations (28) on their mesial and distal surfaces aimed at holding the clasp on insertion and removal. In a mesiodistal view the arms display a groove (29) on their ends to prevent them from being dislodged (FIG. 16).
The connector (27) shows a thickening (30) serving as a stop when the clasp is inserted in the grooves, this clasp by being totally flat (31) allows the slot space to remain free. 2) Prescription-expression clasp (FIG. 17), showing three arms: two lateral arms (32), one inner arm (33) and a connector (34); the lateral arms display indentations (35) aimed at holding the clasp when it is inserted and removed. These arms have grooves on their ends (36) to avoid dislodgement. The inner arm has an irregular shape being wider in its free end (37); this provides more supporting surface to the arm. The center of these arms shows a curvature towards lingual (38) which forces the archwires to seat on the horizontal slot bottom (23). This feature allows the bracket prescription to be expressed by using full size archwires. In a mesiodistal view (FIG. 18), the connector (34) shows a thickening (39) which serves as a stop when the clasp is inserted in the grooves. In this view the curvature of the inner arm towards lingual is observed (38). 3) Esthetic clasp (FIG. 19), this clasp has the modality of a wider and flatter inner arm (4). The lateral arms (41) display indentations (42) serving as a hold for the clasp when it is inserted and removed. On their ends the lateral arms show a groove (43) to prevent them from being dislodged. The connector (44) joins the lateral arms to the inner one. In a mesiodistal view (FIG. 20) the connector (44) shows a thickening (45) serving as a stop when the clasp is inserted in the grooves. This clasp may be manufactured in materials allowing it to have different colors: ivory-colored for adult patients and in color for young patients
This totally adjustable bracket system works as follows: all of the brackets have a predetermined prescription of inclination, angulation and movement of first order which the clinician will be able to modify at will by means of the measuring and perspective prescription appliance, whose patent is being taken out. Once the inclination of the tooth labial surface is obtained, including molars, the information is carried to the brackets by means of the welding unit that permits joining the base to the body (FIG. 21a, b); when the base and the body are placed on the welding unit (FIG. 22a, b), the torque is adjusted having the possibility of incrementing or decreasing it up to ten degrees (FIG. 23a, b); following this the angulation is adjusted (FIG. 24a, b) having the possibility of increasing or decreasing it up to ten degrees; an anti-rotation movement of up to five degrees may be added (FIG. 25a, b); the adjustment for the first order movement is achieved by using different base thicknesses.
The brackets may be placed by means of indirect bonding once they have the individualized prescription; the self-ligating clasp modality allows their use in order to generate low friction during the tooth movement, or to use them with a different esthetic appearance, or when there is a need to allow the expression of the prescription by inserting full size archwires, it also allows to place metallic or elastic ligature.
The above-mentioned features eliminate the need to perform adjustments in the archwires, so the orthodontist really would be able to work with straight archwire systems; however, the most important thing of this invention is that it fits to the individual characteristics of the person.